Up-to-date take-apart bridges for use during disasters etc. must be capable not only of being emplaced in a very short time and adapted to various spans but also of being transported in widths that are permissible on ordinary roads. Take-apart bridges for military use in the field should also, in order to prevent discovery, present as low a silhouette as possible.
One technique frequently employed for emplacing a bridge of this type involves launching it from the near to the far bank over the span that is to be covered. When the spans are wide (e.g. more than 35 m), it is usually impossible to launch the bridge itself over the span because too heavy a counterweight would be needed to maintain equilibrium at the near bank. A known practice in such cases is to initially launch a cantilever (probe) that weighs considerably less per unit of length and then slide the bridge itself out over the cantilever. The bridge is then supported on the cantilever until its outer end reaches the far bank.
Another practice known in conjunction with drive-over bridges is to exploit the space between the drive-over to accommodate the cantilevers, which are left there once the bridge has been emplaced to reduce the load to be accepted by the structure.
Known take-apart drive-over bridges cannot simultaneously satisfy all the requirements of rapid emplacement over long spans, transportation in permissible widths, and as low a silhouette as possible. Either the sections of the cantilever and drive-overs are assembled separately on the near bank, which takes a long time, or, although the bridge-section transport units already comprise the two drive-over sections, they are too wide for ordinary streets and roads and do not as yet include an associated cantilever section.